Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-05-15
2004-06-01
Nguyen, Lamson (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S009000, C347S011000, C347S020000, C347S022000, C347S029000, C347S019000, C347S065000, C347S068000, C347S070000
Reexamination Certificate
active
06742859
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a liquid jetting apparatus having a head member capable of jetting liquid from nozzles, such as an ink-jet recording apparatus having a recording head capable of jetting ink from nozzles to form dots on a recording medium. In particular, this invention is related to a liquid jetting apparatus which can prevent viscosity of liquid in nozzles from increasing.
BACKGROUND OF THE INVENTION
An ink-jet recording apparatus such as an ink-jet printer or an ink-jet plotter has a recording head that is movable along a main scanning direction. The recording head has nozzles capable of jetting ink. For example, the nozzles are communicated to pressure chambers which can expand and contract respectively. In the case, the ink in the nozzles can be jetted by expanding and contracting of the pressure chambers.
On the other hand, the ink-jet recording apparatus is adapted to feed a recording medium such as a paper along a subordinate scanning direction, which is perpendicular to the main scanning direction. Thus, the nozzles of the recording head can jet ink to form an image or a character on the recording medium in cooperation with moving the recording head and the recording medium according to recording data.
The ink in the nozzles of the recording head is exposed to air. Thus, solvent of the ink such as water may gradually evaporate to increase a viscosity of the ink in the nozzles. In the case, quality of printed (recorded) images may deteriorate because the ink having a great viscosity may be jetted toward a direction deviated from a normal direction.
To prevent the viscosity of the ink in the nozzles from increasing, some measures have been proposed. One of the measures is to cause a meniscus of the ink to minutely vibrate to stir the ink. The meniscus means a free surface of the ink exposed at an opening of the nozzle.
For stirring the ink, the meniscus may be vibrated to a jetting direction of the ink and to a contracting direction opposed to the jetting direction by turns in such a manner that the ink may not be jetted. The vibration of the meniscus can be also carried out by expanding and contracting of the pressure chambers. Owing to the vibration of the meniscus, the ink at the opening of the nozzle may be stirred to prevent the viscosity of the ink from increasing.
The stirring of the ink may be carried out during a recording operation. For example, the stirring may be carried out while a carriage carrying the recording head is being accelerated after starting a main scanning, or while a recording operation for a line is being carried out. In the stirring while the carriage is being accelerated, a micro-vibrating operating signal for micro vibrating is supplied to the recording head to cause all menisci in the nozzles to minutely vibrate. In the stirring while the recording operation is being carried out, a pulse signal for micro vibrating is generated from a jetting operating signal for jetting ink, and the pulse signal is supplied to the recording head. Thus, the ink in the nozzles not in the recording (jetting) operation may be stirred.
In addition, Japanese Patent Laid-Open Publication No. 2000-21507 has described that it is effective to cause menisci of ink in nozzles to minutely vibrate during a predetermined time from a suitable timing just before jetting a drop of the ink or from a suitable timing just before jetting a drop of the ink till another suitable timing just before jetting a drop of the ink.
Japanese Patent Laid-Open Publication No. 2000-21507 has also proposed a pre-printing micro-vibrating operation just before jetting a drop of the ink. In addition, Japanese Patent Laid-Open Publication No. 2000-21507 has disclosed that an out-of-printing micro-vibrating operation can be performed further before the pre-printing micro-vibrating operation.
However, if an ink whose viscosity tends to increase is used (for example, a kind of pigment ink or a kind of high-density dye ink), solvent of the ink may easily evaporate to increase a viscosity of the ink, even for a short time between a completion of a main scanning operation and a start of a next main scanning operation. In the case, it is possible that the state wherein the viscosity of the ink has been increased may not be dispelled sufficiently by means of the out-of-printing micro-vibrating operation or the pre-printing micro-vibrating operation after starting the next main scanning operation.
SUMMARY OF THE INVENTION
The object of this invention is to solve the above problems, that is, to provide a liquid jetting apparatus that can prevent a viscosity of liquid from increasing, even if a liquid whose viscosity tends to increase is used, such as an ink-jet recording apparatus.
In order to achieve the object, the invention is a liquid jetting apparatus comprising: a head member having a nozzle; a supporting member that can support a medium onto which liquid is to be jetted; a scanning mechanism that can cause the head member to relatively move with respect to the medium; a liquid jetting unit that can jet liquid from the nozzle; an area storing unit that stores a relative area to which liquid can be jetted from the nozzle while the head member is caused to relatively move by the scanning mechanism; an out-of-jetting micro-vibrating-area setting unit that can set out-of-jetting micro-vibrating areas before and after the relative area to which liquid can be jetted from the nozzle, based on the relative area to which liquid can be jetted from the nozzle; a scanning-position-information outputting unit capable of outputting head-position information that represents a relative position of the head member while the head member is caused to relatively move by the scanning mechanism; a micro-vibrating unit that can cause liquid in the nozzle to minutely vibrate; and an out-of-jetting micro-vibrating controlling unit that can cause the micro-vibrating unit to operate when the head member is located in the out-of-jetting micro-vibrating areas, while the head member is caused to relatively move by the scanning mechanism, based on the out-of-jetting micro-vibrating areas and the head-position information.
According to the above feature, since the out-of-jetting micro-vibrating areas are set before and after the relative area to which liquid can be jetted from the nozzle, it can be effectively prevented that a viscosity of the liquid increases between a completion of a scanning operation and a start of a next scanning operation.
Alternatively, the invention is a liquid jetting apparatus comprising: a head member having a nozzle; a supporting member that can support a medium onto which liquid is to be jetted; a scanning mechanism that can cause the head member to relatively move with respect to the medium; a liquid jetting unit that can jet liquid from the nozzle; an out-of-jetting micro-vibrating-area setting unit that can set out-of-jetting micro-vibrating areas before and after a liquid-jetting area to which liquid is to be jetted from the nozzle while the head member is caused to relatively move by the scanning mechanism, based on jetting data; a scanning-position-information outputting unit capable of outputting head-position information that represents a relative position of the head member while the head member is caused to relatively move by the scanning mechanism; a micro-vibrating unit that can cause liquid in the nozzle to minutely vibrate; and an out-of-jetting micro-vibrating controlling unit that can cause the micro-vibrating unit to operate when the head member is located in the out-of-jetting micro-vibrating areas, while the head member is caused to relatively move by the scanning mechanism, based on the out-of-jetting micro-vibrating areas and the head-position information.
According to the above feature, since the out-of-jetting micro-vibrating areas are set before and after the liquid-jetting area to which liquid is to be jetted from the nozzle while the head member is caused to relatively move by the scanning mechanism based on jetting data, it can be effectively
Tanaka Ryoichi
Yonekubo Shuji
Liang Leonard
Nguyen Lamson
Seiko Epson Corporation
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